Many types of building work involve drilling into and/or demolishing walls and concrete structures, with hand held tools such as drills and combined hammer drills. Such drilling work typically involves releasing large amounts of dust. German Patent Application DE4038941 describes a dust extraction system for a portable power drill in which the drill bit passes into a shroud held flush against the wall or structure being drilled. The shroud is connected to a source of suction which removes dust from the shroud as it is being produced.
This prior art dust extraction system suffers from the drawback that the air inlets for the vacuum source are disposed very near to, or on the surface being drilled. As a result of this, the inlets can become easily blocked thereby reducing the effectiveness of the dust extractor.